This General Parameters rollout is displayed for photometric lights. These controls turn a light on and off, and exclude or include objects in the scene. They also let you set the type of light distribution.
On the Modify panel, the General Parameters rollout also lets you control the light’s target object and change the light from one type to another.
The General Parameters rollout also lets you turn shadow-casting on or off for the light, and choose which type of shadow the light uses. See Shadow Types and Shadow Controls and Shadow Parameters.
Shadows group, make sure On is selected.
The light will now cast shadows when you render the scene.
Left: With Spotlight distribution, the projection cone can truncate shadows.
Right: With Uniform Spherical distribution, the light casts complete shadows.
To have a light use the global settings for shadows:
When Use Global Settings is on, the other shadow controls are set to the values used by all other shadow-casting lights in the scene that have Use Global Settings set.
Changing the affected parameters for one light with Use Global Settings set, changes them for all lights with Use Global Settings set.
To set a light's shadow parameters individually:
The settings revert to the individual settings for the light.
By default, Shadow Map is the active shadow type. In the Shadow Map Params rollout, the default settings are: Map Bias=1; Size=512; Sample Range=4.0; Absolute Map Bias=Off.
Scene with shadow-mapped shadows
Shadows rendered using default parameter settings
Use controls on the Area Shadows rollout to adjust the shadow properties.
To cast advanced ray-traced shadows:
Advanced ray-traced shadows are similar to ray-traced shadows, however they provide control over antialiasing, letting you fine-tune how shadows are generated.
Use controls on the Advanced Ray-traced Params rollout to adjust the shadow properties.
To cast shadow-mapped shadows:
Ray-traced shadows are generated by tracing the path of rays sampled from a light source. Ray-traced shadows are more accurate than shadow-mapped shadows.
To keep an object from casting shadows:
Select the object.
The Object Properties dialog is displayed.
To make an object not receive shadows:
Select the object.
The Object Properties dialog is displayed.
Now when you render the scene, the object receives no shadows.
(Both Create panel and Modify panel) Turns the light on and off. When On is on, shading and rendering use the light to illuminate the scene. When On is off, the light is not used in shading or rendering. Default=on.
In viewports, the interactive renderer shows the effect of turning lights on or off.
Determines whether the renderer uses shadow maps, ray-traced shadows, advanced ray-traced shadows, or area shadows, to generate shadows for this light.
The “mental ray Shadow Map” type is provided for use with the mental ray renderer. When you choose this shadow type and enable shadow maps (on the Shadows & Displacement rollout of the Render Setup dialog), shadows use the mental ray shadow-map algorithm. If this type is chosen but you render with the default scanline renderer, no shadows appear in the rendering.
Each shadow type has its particular controls:
Turn on to use global settings for shadows cast by this light. Turn off to enable individual control of the shadows. If you choose not to use the global settings, you must choose which method the renderer will use to generate shadows for this particular light.
When Use Global Settings is on, the shadow parameters switch over to show you what the global settings are. This data is shared by every other light of this class. When Use Global Settings is off, the shadow parameters are specific to that particular light.
Excludes selected objects from the effects of the light. Click this button to display the Exclude/Include dialog.
Excluded objects still appear lit in shaded viewports. Exclusion takes effect only when you render the scene.
Light Distribution (Type) group
The light distribution drop-down list lets you choose the type of light distribution. There are four options:
When you choose this option, the Distribution (Photometric File) rollout opens on the command panel.
When you choose this option, the Distribution (Spotlight) rollout opens on the command panel.
Uniform distribution, whether diffuse or spherical, has no additional settings, so these choices don’t display a special Distribution rollout.
Uniform spherical distribution, as its name implies, casts light equally in all directions.
Uniform diffuse distribution casts diffuse light in one hemisphere only, as if the light were emitted from a surface.
Spotlight distribution casts a focused beam of light like a flashlight, a follow spot in a theater, or a headlight. The light's beam angle controls the main strength of the beam, and the field angle controls the “spill” of light outside the main beam.
Create panel 
(Lights) 
Modify panel